This invention relates to a glow discharge heating apparatus for heating a liquid through the utilization of a glow discharge established between a pair of electrodes involved.
Japanese laid-open patent application No. 6252/1976 describes and claims a glow discharge heating apparatus for heating a liquid by utilizing a phenomenon that a glow discharge occurring between a pair of cathode and anode electrodes heats the cathode electrode to an elevated temperature. The glow discharge heating apparatus disclosed in the cited patent application comprises a hollow cylindrical enclosure, a tubular cathode electrode coaxially entended and sealed through the enclosure, and having both ends open, a hollow cylindrical anode electrode disposed in the enclosure to surround the cathode electrode substantially throughout the length thereof to form an annular discharge gap therebetween, a source of DC voltage connected across the cathode and anode electrodes to cause a glow discharge therebetween. The cathode electrode is heated with the glow discharge to directly heat a liquid flowing therethrough.
Heating apparatus of this type referred to have instantaneously heated the liquid with the simple construction and still with the high efficiency. However, where high currents are required to establish the glow discharge between the electrodes, it has been difficult to sustain the stabilized glow discharge therebetween. There have been a fear that the glow discharge will transit to an arc discharge as the case may be. Also the electrodes have been heated to be axially expanded. This might result in a fear that the apparatus is broken.
Further it has been difficult to reliably control the glow discharge because of the absence of a control circuit for starting and extinguishing the glow discharge.
Accordingly it is an object of the present invention to eliminate the disadvantages of the prior art practice as above described by the provision of a new and improved glow discharge heating apparatus capable of always sustaining a stabilized glow discharge.
It is another object of the present invention to provide a new and improved glow discharge heating apparatus including means for absorbing thermal strains developed in electrodes thereby to provide a construction difficult to be broken.
It is still another object of the present invention provide a new and improved glow discharge heating apparatus including a control circuit for easily controlling a glow discharge occurring across a pair of electrodes involved.